The present invention relates to a suspension for supporting the slider of a disc drive incorporated in an information processing apparatus such as personal computer and portable computer, and more particularly to an improvement of its wiring portion and others.
In a head of a magnetic disc drive or optical-magnetic disc drive, the slider is slightly floating above the disc rotating at high speed. A transducer is built in this slider, and recording or reproducing of data in the disc is performed through this transducer. Accordingly, the slider is supported by a suspension so as to be in a floating state from the disc.
As this kind of suspension, as disclosed, for example, in Jpn. Pat. Appln. KOKAI Publication No. 5-282642, the slider is fixed on a gimbal (or also known as flexure) provided in a load beam. A known suspension 1 shown in FIG. 8 has a flexure 3 composed of a very thin metal plate fixed to the leading end of a load beam 2. A tongue 4 is provided in this flexure 3, and a slider 5 is supported by this tongue.
At both sides of the tongue 4, a pair of outrigger portions 6 are provided. The tongue 4 is inclined at a slight pitch angle of 2 to 3 or less degrees to the outrigger portions 6 as seen from its side. A terminal 7 of the slider 5 is connected to a wiring portion 8. The wiring portion 8 is provided in the flexure 3, and an outer lead wire not shown in the drawing is connected to the other end of the wiring portion 8.
The wiring portion 8 is generally composed of an electric insulating layer made of synthetic resin such as polyimide formed on a metal plate for composing the flexure 3, an electric conductive layer made of copper or the like provided on this electric insulating layer, a guard layer made of synthetic resin such as polyimide laminated as required on this electric conductive layer, and others. The electric conductive layer is patterned by known film forming technology and etching.
The synthetic resin such as polyimide used in the electric insulating layer and guard layer is deformed by expansion or shrinkage due to temperature changes, moisture absorption, or dehumidifying. Accordingly, if the wiring portion is fixed to a thin and low-rigid metal plate such as the outrigger portions, in case the wiring portion is deformed, the outrigger portions may be also deformed. The slider fixed on the tongue is largely changed in its floating characteristic from the disc depending on its fixed state, and therefore if the flexure is deformed as mentioned above, the slider position is also changed, and the desired floating characteristic may not be obtained.
In the case of bending process for providing the tongue with the pitch angle, tensile stress or torsional stress may occur in the wiring portion due to processing. Such stress works as a spring-back force to return the processed shape to the original state. Thus, the rigidity of the wiring portion is a hindrance to bending process of the tongue at high precision. In particular, the problem is more obvious when a relatively rigid metal such as rolled copper is used in the electric conductive layer of the wiring portion.